40 patients at high risk of post operative systemic inflammatory response syndrome after an elective cardiac surgery with CPB were included in this prospective observational study. Patients were studied during the first 48 postoperative hours. Microcirculation of the thenar eminence was analyzed by NIRS technology, through the StO2 and the resaturation slope after an ischemic challenge. Organ dysfunction was assessed with the SOFA score.